1. Field of the Invention
The present invention relates to an integrated circuit for use in a tape recorder and to a tape recorder incorporating the integrated circuit. The invention further relates to the means for converting the tape recorder from the recording to the playback mode of operation and to means for insuring temperature stable operation.
2. Description of the Prior Art
The organization of electronic products which were originally designed to be fabricated from discrete electrical components has been very significantly changed with the advent of the integrated circuit. Integrated circuit technology has permitted a very significant growth in electronic circuit complexity on the integrated circuit at a very small incremental cost. By comparison, the cost of adding connections to the integrated circuit has remained high and the costs of "outboarded" or non-integrated electrical components has remained high. Ideally, the product when integrated will have all of the functions of a non-integrated product costing substantially more.
As applied to a tape recorder, it is desirable that the tape recorder have all of the essential functions for recording and playback and that the active electronics for all of these functions be integrated. In the recording mode, for instance, an amplifier is required for recording, and an automatic level control should be provided to standardize the signal level. In addition, a microphone power supply and biasing means for the erase head are normally required. In the playback mode, it is desirable to have an amplifier which operates with the playback head output and which may be used for reproducing the signal. In general, these functions should be provided in a manner which minimizes the external pin count required by the integrated circuit and which permits optimum use of the essential outboarded electrical components. For instance, in previous discrete recorder designs, a single amplifier was generally used for both playback pre-amplification and recording. The choice required complicated mechanical play/record mode switching. Using integrated circuit technology, the cost of separate amplifiers is not prohibitive. When separate amplifiers are used, the switching requirement may be simplified. When much of the switching can be done internal to the integrated circuit, even further simplification in the external switching requirement may be achieved.